A virtual reality (VR) system replicates an environment that simulates physical presence in places in the real world or an imagined world using entirely-computer-generated three-dimensional (3D) imagery of “scenes” within this world. Similarly, an augmented reality (AR) system “augments” physical presence in the real world through computer-generated 3D imagery that overlies contemporaneously captured imagery of the real world. Thus, VR and AR systems both seek to provide an accurate sense of “presence” in the real, augmented, or imagined world. Typically, this sense of presence is facilitated through the use of a head mounted display (HMD) that provides separate left-eye and right-eye displays. The displays together present a stereoscopic, or 3D, representation of a scene in the represented world, where the presented scene reflects the user's relative perspective of the scene based on the user's current pose (that is, the location and orientation of the user's head relative to a reference coordinate frame for the depicted scene).
HMD-based VR and AR systems display 3D imagery as a sequence of display frames, each display frame rendered based on a corresponding detected head pose and persisting for a particular period of time. However, as an HMD generally permits a user to move freely about, the user's head may have significantly rotated in the time between the initiation of the rendering of a frame and the display of the resulting rendered frame. As such, the imagery displayed at the HMD at a particular point in time may lag behind the user's head movements. This dissonance between the user's perceived orientation within a scene and the orientation of the perspective of the scene presented on the HMD can lead to user disorientation, or what is often referred to as “virtual reality sickness”. Thus, to reduce or eliminate user disorientation and thereby provide improved presence, HMD-based VR and AR systems seek to minimize the motion-to-photon latency; that is, the latency between user head/eye movement and when photons representing a scene from in the resulting new pose hit the user's eye.